This grant will provide support for continuation of participation of the Radiotherapy Division of the University of Puerto Rico School of Medicine in the Radiation Therapy Oncology Group. The R.T.O.G. is constituted by a group of academic institutions involved in prospective collaborative clinical research in radiation therapy of cancer. The University of Puerto Rico began its participation in 1972. Research projects approved by the R.T.O.G. will be carried out by this radiation therapy academic program, which utilizes the facilities of the Puerto Rico Nuclear Center and a group of affiliated institutions: The choice of patients, randomization, treatment techniques, tumor and normal tissue reaction evaluation, follow-up, form preparation, etc. will be performed in accordance to the protocols approved by the R.T.O.G. Radiological physics and statistical work will be controlled by the corresponding central physics and statistical centers.